The present invention relates to a water content-measurement method and a water content-measurement apparatus for measuring the water content of an object to be measured, such as a paper, a film, etc., using light, and to an electrical component-fabrication method using the measurement.method or the measurement apparatus.
Concerning a technique for measuring the water content of an object to be measured, there is a two-color infrared water content-measurement device, using absorbed light of 1.94 xcexcm wave length and reference light of 1.7 or 1.8 xcexcm wave length, for obtaining a measure of the water content based on the ratio of two absorption degree signals of the absorbed light and the reference light. Further, for example, Japanese Patent Application Laid-Open Hei 5-164690 discloses a three-color water content-measurement device, which is not affected by the type of object to be measured, or the humidity in the air, by using absorption light of 1.96 and 2.0 xcexcm wave lengths, and reference light of 1.9 and 2.1 xcexcm wave lengths. Also, for example, Japanese Patent Application Laid-Open Sho 60-93334 discloses a water content-measurement method suitable for measurement of high water content, which uses measurement light of 1.76-1.87 xcexcm wave length, and reference light of 1.7 xcexcm wave length.
However, in the conventional water content-measurement method and apparatus as described above, since an output measurement signal indicating water content deviates due to even a small difference between wave length values 1.7 and 1.8 xcexcm, a high measurement accuracy cannot be realized. Further, the size of the measurement apparatus becomes large because monochromatic light is obtained from continuous spectrum light via a spectrograph or a filter.
Moreover, in the fabrication of electrical components such as transformers, motors, etc., since an insulating paper covering a coil conductor absorbs moisture during insulation paper-covering operations or electrical component-assembling operations, a dry process is performed after the assembling is finished. However, since there has not been a portable water content-measurement device, a problem results in that it is difficult to heuristically dry insulation paper, etc., in just proportions, that is, needless time is consumed by overabundant dry-processing, or the insulation performance of the insulating papers is deteriorated by the shortage in drying the insulating papers due to improperly shortened dry-processing.
An object of the present invention is to provide a water content-measurement method and a water content-measurement apparatus which is capable of measuring the water content of an object be measured, with a high degree of accuracy.
Another object of the present invention is to provide a water content-measurement method which uses a water content-measurement apparatus of reduced size, and which can be compactly composed.
Further, another object of the present invention is to provide an electrical component-fabrication method which is capable of efficiently fabricating an electrical component having excellent insulation characteristics.
From results of examining the relationship between water content and reflectance spectroscopic characteristics of an object to be measured, it has been found that the water content of an object to be measured can be calculated from a change in the reflective-absorbance difference between, or a reflective-absorbance ratio of light beams of two specific wave length values.
The present invention provides a water content-measurement method in which the surface of an object to be measured is irradiated with a light beam having a wave length at which reflective absorbance is largely affected by water content, and a light beam of another wave length at which reflective absorbance is hardly affected by water content, and the reflective absorbance of each light beam is obtained by measuring the intensity of reflected light in each light beam. The method comprises the steps of: irradiating the surface of the object to be measured, with at least two kinds of monochromatic light beams of different wave length values, one of the wave length values being less than 1350 nm, the light beams being directed to the surface of the objective member by a light-guiding device for light-irradiation; measuring the intensity of reflected light in each of the light beams, which light is reflecting from the surface of the object, by directing the reflected light to a light intensity-measurement unit, using a light-guiding device for light reception; obtaining the reflective absorbance (Axcex) of each light beam, using the equation (1); calculating a reflective-absorbance difference (Axcex) between, or a reflective-absorbance ratio (Axcexxe2x80x2) of, the respective light beams, using the equation (2) or the equation (3), respectively; and estimating the water content of the measured object by using the calculated reflective-absorbance difference (xcex94Axcex) or the calculated reflective-absorbance ratio (Axcexxe2x80x2), and the relationship between water content, and reflective-absorbance differences (xcex94Axcex) or reflective-absorbance ratios (Axcexxe2x80x2), the relationship being stored in a memory device in advance.
Here, Axcex=xe2x88x92log (Ixcex/I0,xcex)xe2x80x83xe2x80x83(1),
xcex94Axcex=Axcex1xe2x88x92Axcex2 (xcex1 greater than xcex2)xe2x80x83xe2x80x83(2), and
Axcexxe2x80x2=Axcex1/Axcex2 (xcex1 greater than xcex2)xe2x80x83xe2x80x83(3),
where I: the intensity of light reflecting from the surface of a standard white board, I0: the intensity of the light reflecting from the surface of the measured object, and xcex2: a wave length value less than 1350 nm.
Further, the present invention provides a water content-measurement apparatus for measuring water content by irradiating the surface of an object to be measured with a light beam having a wave length at which reflective absorbance is largely affected by water content, and a light beam of another wave length at which reflective absorbance is hardly affected by water content. The reflective absorbance of each light beam based on a measured intensity value of reflected light in each light beam. The apparatus comprises: a light source for emitting at least two kinds of monochromatic light beams of different wave lengths, one of the wave length values being less than 1350 nm; a light-guiding device for light-irradiation, for directing the light beams emitted from the light source to the surface of the objective member; a light-guiding device for directing reflected light in each of the light beams, which light is reflecting from the surface of the object; a light intensity-measurement unit for measuring the intensity of light radiated from the light-guiding device; and a calculation and control unit which obtains the reflective absorbance (Axcex) of each light beam, calculates a reflective-absorbance difference (xcex94Axcex) between, or a reflective-absorbance ratio (Axcexxe2x80x2) of, the respective light beams, and estimates the water content of the measured object by using the calculated reflective-absorbance difference (xcex94Axcex) or the calculated reflective-absorbance ratio (Axcexxe2x80x2), and the relationship between water content, and reflective-absorbance differences (xcex94Axcex) or reflective-absorbance ratios (Axcexxe2x80x2), the relationship being stored in a memory device in advance.
Furthermore, the present invention provides a method of fabricating an electrical component in which a coil conductor covered with an insulating paper is contained in a case, and insulation oil is poured into the case after the coil conductor covered with the insulating paper is dried. The method comprises the steps of: irradiating the surface of the insulating paper with at least two kinds of monochromatic light beams having different wave length values, one of the wave length values being less than 1350 nm, said light beams being directed onto the surface of the insulating paper by a light-guiding device for light-irradiation; measuring the intensity of reflected light in each of the light beams, which light is reflecting from the surface of the insulating paper, by directing the reflected light to a light intensity-measurement unit, using a light-guiding device; obtaining the reflective absorbance (Axcex) of each light beam, using the equation (1); calculating a reflective-absorbance difference (xcex94Axcex) between, or a reflective-absorbance ratio (Axcex) of, the respective light beams, using the equation (2) or (3), respectively; estimating the water content of the measured object member by using the calculated reflective-absorbance difference (xcex94Axcex) or the calculated reflective-absorbance ratio (Axcexxe2x80x2), and the relationship between water content, and reflective-absorbance differences (xcex94Axcex) or reflective-absorbance ratios (Axcexxe2x80x2), the relationship being stored in a memory device in advance; drying the coil conductor covered with the insulating paper until the water content of the coil conductor becomes less than a predetermined value; and pouring insulation oil into the case.
Here, Axcex=xe2x88x92log (Ixcex/I0,xcex)xe2x80x83xe2x80x83(1),
xcex94AxcexAxcex1xe2x88x92Axcex2 (xcex1 greater than xcex2)xe2x80x83xe2x80x83(2), and
Axcexxe2x80x2=Axcex1/Axcex2 (xcex1 greater than xcex2)xe2x80x83xe2x80x83(3),
where I: the intensity of light reflecting from the surface of a standard white board, I0: the intensity of light reflecting from the surface of the measured object, and xcex2: a wave length value less than 1350 nm.
In addition, the present invention provides a method of fabricating an electrical component in which a stator core is wound by a coil conductor covered with an insulating paper, and a varnishing process is performed on the stator core and the coil conductor after the stator core wound by the coil conductor covered with the insulating paper is dried. The method includes the steps of: irradiating the surface of the insulating paper with at least two kinds of monochromatic light beams having different wave lengths, one of the wave length being less than 1350 nm, the light beams being directed onto the surface of the insulating paper by a light-guiding device for light-irradiation; measuring the intensity of reflected light in each of the light beams, which light is reflecting from the surface of the insulating paper, by directing the reflected light to a light intensity-measurement unit, using a light-guiding device; obtaining the reflective absorbance (Axcex) of each light beam, using the equation (1); calculating a reflective-absorbance difference (xcex94Axcex) between, or a reflective-absorbance ratio (Axcexxe2x80x2) of, the respective light beams, using the equation (2) or (3), respectively; estimating the water content of the measured object by using the calculated reflective-absorbance difference (xcex94Axcexxe2x80x2) or the calculated reflective-absorbance ratio (Axcexxe2x80x2), and the relationship between water content, and reflective-absorbance differences (xcex94Axcex) or reflective-absorbance ratios (Axcex), the relationship being stored in a memory device in advance; drying the coil conductor covered with the insulating paper until the water content of the coil conductor becomes less than a predetermined value; and performing a varnishing process for the stator core and the coil conductor.
Here, Axcex=xe2x88x92log (Ixcex/I0,xcex)xe2x80x83xe2x80x83(1),
xcex94AxcexAxcex1xe2x88x92Axcex2 (xcex1 greater than xcex2)xe2x80x83xe2x80x83(2), and
Axcexxe2x80x2=Axcex1/Axcex2 (xcex1 greater than xcex2)xe2x80x83xe2x80x83(3),
where I: the intensity of light reflecting from the surface of a standard white board, I0: the intensity of light reflecting from the surface of the measured object, and xcex2: a wave length less than 1350 nm.
Further, concerning the wave lengths of the monochromatic light beams, it is preferable to set xcex1 in a range of 1400-2000 nm, and B in a range of 600-1350 nm.
Moreover, a semiconductor laser diode or a light emission diode, which emits light having a peak in a wave length range of 600 nm-2000 nm, can be used for the monochromatic light source.
Also, it is preferable to use a glass fiber for the light-guiding device for light-irradiation, and the light-guiding device for light-reception.